Capable men have differed on this for years. Here are three suggestions for differentiating between these passages.

First, the phrase, "sons of God," does not necessarily mean angels. Three times it does (Job 1:6; 2:1; 38:7), but at least 4 times this word describes Israels relationship to God as "sons" (Exodus 4:22; Hosea 1:10; Deuteronomy 14:1; Psalm 73:15). This expresses a relationship of favor with God, distinguished from all others; that may be its thought in Genesis 6.

Second, in their context, these verses are the bridge between the genealogy of the godly in chapter five and the corruption that demanded the righteous judgment of the flood. Since other passages hold men - not fallen angels - responsible for the evil of those days (Genesis 6:12, 13; Job 22:15-17; 2 Peter 2:5), the context favors the view that a lack of separation by a favored generation hastened the corruption.

The context in Jude also seems to differentiate the two passages. With Egypt and Sodom, these angels form part of one of Judes many triplets. As with those referred in Jude 4, these all sinned while privileged and then suffered judgment, as those in verse 4 would. If Lucifers thought brought immediate judgment (Isaiah 14:12, 13), the sin of these in Jude 6 must likewise have called for immediate banishment to everlasting chains. Even if the "sons of God" in Genesis 6 were angels, they were previously fallen (judged) angels, who for a prolonged period - as is supposed - cohabited with women. This is not an illustration of those who sin while privileged and therefore suffer severely.